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Biomedical subjects

I Brook

Publications and source records attributed to I Brook.

At least 343 records · Page 19Linked to original sources
PubMed1984

Significance of encapsulated Bacteroides melaninogenicus and Bacteroides fragilis groups in mixed infections.

Organisms of the Bacteroides melaninogenicus and Bacteroides fragilis groups are often found mixed with facultatively anaerobic organisms in infections. The relative importance of these Bacteroides groups and facultative anaerobic pathogens in mixed infections was investigated in a subcutaneous abscess model in mice. This was determined by observing the effect of antimicrobial therapy directed against one or both organisms present in the abscess. Clindamycin or metronidazole was used for treatment of infections caused by Bacteroides species, and either gentamicin, penicillin, ampicillin, or oxacillin was used for treatment of infections caused by facultative flora. In almost all instances the aerobic counterparts in the infection were more important than the unencapsulated Bacteroides species. On the other hand, encapsulated B. melaninogenicus group organisms were found to be more important in abscess formation than were group A streptococci, Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. Encapsulated B. fragilis group organisms were found to be more important than or as important as Escherichia coli and group D streptococci and less important than S. aureus, group A streptococci, and K. pneumoniae in induction of subcutaneous abscesses. This study demonstrates that encapsulated Bacteroides species are a factor that should be considered in the treatment of mixed infections with antibiotics.

Abscess↗
PubMed1984

Pathogenicity of anaerobic gram-positive cocci.

The pathogenicity of 20 strains of facultative or anaerobic gram-positive cocci (AGPC) was investigated by injecting them alone or mixed with other flora into mice, utilizing the subcutaneous abscess model. Abscesses induced by a mixture of two organisms were uniformly larger than those induced by single organisms. The relationships among seven AGPC strains, eight aerobes, and two Bacteroides spp. were determined by treating the infected animals with antibiotics and observing the effect of therapy directed against one or both organisms present in the abscess. A total of 70 different combinations were tested. As judged by their responses to antimicrobial therapy, facultative cocci or AGPC were relatively more important than the other species in 6 combinations, equally important in 35 combinations, and less important in 29 combinations. The AGPC most often found to be equal to or more important than the other bacteria were Peptococcus magnus, Streptococcus constellatus, and Peptostreptococcus anaerobius. Proteus mirabilis, Escherichia coli, and Staphylococcus aureus were frequently found to be of more importance than the AGPC.

Abscess↗
PubMed1984

Recovery of aerobic and anaerobic bacteria from irradiated mice.

Anaerobic and aerobic bacteria were often found as mixed infections in 225 lethally irradiated mice. Of a total of 57 mice that were sacrificed, aerobic bacteria were recovered exclusively in 9 (27%) of the 34 culture-positive mice, anaerobic bacteria were recovered exclusively in 15 (44%), and mixed aerobic and anaerobic flora were recovered in 10 (29%). The predominant organisms were anaerobic cocci Escherichia coli, Proteus mirabilis, Staphylococcus spp., and Bacteroides spp.

Animals↗
PubMed1984

Rapid method for detecting beta-lactamase producing bacteria in clinical specimens.

The use of liquid media to detect the production of beta-lactamase by beta-lactamase producing organisms has been compared with the conventional method of inoculation on to agar media. Pharyngeal cultures were obtained from 162 children treated with penicillin for acute tonsillitis. beta-lactamase producing organisms were detected within 72 h in 80 (49%) of the specimens inoculated on to agar media, while beta-lactamase production was found in 76 (47%) of the specimens after their incubation in liquid media for 24 h. Twenty one of the cultures were positive only after anaerobic incubation while in liquid media while nine were positive only after aerobic incubation. Incubation in liquid media enabled detection of beta-lactamase activity in 53 of the 76 (70%) specimens within 12 h.

Aerobiosis↗
PubMed1984

In vivo protection of penicillin-susceptible Bacteroides melaninogenicus from penicillin by facultative bacteria which produce beta-lactamase.

We investigated the possibility that beta-lactamase producing strains of Klebsiella pneumoniae and Staphylococcus aureus can protect organisms of the Bacteroides melaninogenicus group from penicillin. A mixed infection was induced in mice in the form of a subcutaneous abscess involving a penicillin-susceptible encapsulated B. melaninogenicus, and a beta-lactamase producing strain of either K. pneumoniae or S. aureus. The infected animals were treated for 7 days with single or combined antimicrobial therapy. The single agents used were penicillin, clavulanic acid, metronidazole, and gentamicin. The antimicrobial combinations were penicillin and clavulanic acid, penicillin and gentamicin, and metronidazole and gentamicin. Administration of a single agent was effective in treating abscesses caused by susceptible organisms. The only effective therapy for mixed infections was by combination therapy of penicillin and clavulanic acid or metronidazole and gentamicin. This study supports the hypothesis that beta-lactamase producing facultative bacteria may shield their anaerobic counterparts from penicillin therapy, thereby contributing to the persistence of the infection.

Abscess↗
PubMed1984

Emergence of beta-lactamase-producing aerobic and anaerobic bacteria in the oropharynx of children following penicillin chemotherapy.

The acquisition of beta-lactamase-producing aerobic and anaerobic bacteria was investigated in 21 children treated with penicillin for otitis media or pharyngitis and in 18 untreated control children. Beta-lactamase-producers were isolated in three children before and in ten children after treatment (p = 0.04). Although the variety of bacterial species isolated did not change following treatment, beta-lactamase-producing Bacteroides melaninogenicus, B. oralis, and Branhamella catarrhalis were encountered only after therapy, while some beta-lactamase-producing Staphylococcus aureus and Hemophilus influenzae were found before treatment. The incidence of beta-lactamase-producers did not increase in the control children. Spread of beta-lactamase-producers to household contacts by 12 treated and 13 normal control children also was studied. Ten of the treated children and 15 of 33 of the household contacts harbored beta-lactamase-producers, while none were found in normal control children and only two were found in 27 of their household contacts (comparison of the two household contacts, p less than 0.01).

Acute Disease↗
PubMed1984

Changes in the bacterial flora of the external ear canal from the wearing of occlusive equipment.

External otitis has been associated with wearing obstructive gear covering the earlobe and external ear canal. In this study we investigated the changes in the bacterial flora of the external ear canal after wearing rubber hoods. The bacterial flora of external ear canals surfaces was investigated in a group of 19 volunteers who wore rubber hoods for a period of 25 to 30 minutes while doing manual work. The protective effect of 2% acetic acid was tested by instilling it in the left ear of all participants. Staphylococcus epidermidis, Propionibacterium acnes, and alpha-hemolytic streptococci were the predominant isolates from the ear samples. After hoods were worn, there was a substantial increase in the number of these organisms in 7 (36.8%) of the external ears. However, an increase in the bacterial counts in the external ear canals occurred in only 2 (10.5%) of the individuals treated prophylactically with acetic acid drops (P less than 0.02).

Acetates↗
PubMed1984

Detection of cervical incompetence by ultrasound.

Ultrasonography was used to measure the width of the internal os in 96 pregnant women, of whom 43 were considered to have cervical incompetence and were scheduled for cerclage. The remainder of the women were divided into two control groups: (a) 28 women with a normal obstetric history, and (b) 25 women with a history of either previous abortion or traumatic delivery. The mean width of the internal os in the three groups was 25.9 mm +/- 3.7, 15.8 mm +/- 2.7, and 18.2 mm +/- 6.5 respectively; statistically, significant difference were seen between the first group and each of the control groups. All the women in the first control group gave birth successfully at term; of those in the second control group, 5 presented with premature rupture of the membranes. The mean cervical os width in these 5 women was 29 mm, as compared with a mean of 18.2 mm for this group as a whole. We suggest that ultrasonic measurement of the internal os during pregnancy can be a useful and objective new method for the diagnosis of cervical incompetence.

Cervix Uteri↗
PubMed1984

Bacteraemia in hospitalized children.

The results of 3,037 blood cultures taken from hospitalized children during 1977 are reviewed, and 171 patients were considered to have bacteraemia whilst 67 were considered to have contaminants. Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus and Streptococcus spp were found to be the most common organisms associated with 80% of the observed bacteraemias. H. influenzae and groups B and D streptococci were more often isolated in young children (less than 3 years). Group D streptococcal bacteria occurred more in newborns and patients with congenital anomalies. H. influenzae and S. pneumoniae bacteraemias were frequently associated with the presence of a foci of infection. Elevated temperature and an absolute differential cell count, were present in 75% of the patients with bacteraemia.

Adolescent↗
PubMed1984

The significance of anaerobic bacteria in biliary tract infection after hepatic portoenterostomy for biliary atresia.

Aspiration of the biliary atrium was performed in six children who developed cholangitis after hepatic portoenterostomy (Kasai procedure). All aspirates were cultured for aerobic and anaerobic bacteria. Aerobic bacteria were recovered in all six specimens and anaerobic organisms were recovered in three. The predominant aerobic organisms were Klebsiella pneumoniae (four isolates), enterococcus (three isolates, and Escherichia coli (two isolates). The anaerobes recovered were Bacteroides fragilis (two) and Clostridium perfringens (one). These findings demonstrate the recovery of anaerobic as well as aerobic organisms in cholangitis after hepatic portoenterostomy.

Bacteria, Anaerobic↗
PubMed1983

Bacteroides melaninogenicus. Its recovery from tonsils of children with acute tonsillitis.

The presence of encapsulated and abscess-forming organisms belonging to the Bacteroides melaninogenicus group was investigated in 25 children with acute tonsillitis, and in 23 children without tonsillar inflammation (control). Encapsulated organisms of the B melaninogenicus group were found in 23 of 25 children with acute tonsillitis as compared with five of 23 controls. Subcutaneous inoculation into mice of the Bacteroides strains isolated from patients with tonsillitis produced abscesses in 17 of 25 instances, as compared with nine of the 23 of the controls. Group A streptococci were recovered from the tonsils of five children with tonsillitis and from four of the control group. These findings suggest a possible pathogenic role for the B melaninogenicus group in acute tonsillar infection in children.

Abscess↗
PubMed1983

Pathogenicity of encapsulated Bacteroides melaninogenicus group, B. oralis and B. ruminicola subsp. brevis in abscesses in mice.

The pathogenicity of 27 clinical isolates of the Bacteroides melaninogenicus (BM) group and four clinical isolates of B. oralis and B. ruminicola subsp. brevis were investigated by inoculating them into mice and subsequently determining their ability to cause subcutaneous (SC) or intraperitoneal abscesses. Only 11 isolates of BM group and one B. ruminicola induced abscesses in mice, and all were found to be heavily encapsulated on recovery from the abscesses (more than 50 per cent of the organisms were encapsulated). When the other 23 isolates, however, were injected SC in combination with either Klebsiella pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus or Streptococcus pyogenes, abscesses were formed in 16 of the 23 combinations. The Bacteroides spp. recovered from the mixed infection were heavily encapsulated. Capsules also formed in Bacteroides if the organisms were injected together with capsular material or formalin killed cells of K. pneumoniae or encapsulated Bacteroides sp. Once non-encapsulated or only slightly encapsulated strains acquired a capsule, they could induce abscesses on reinoculation into mice.

Abscess↗
PubMed1983

Antibiotic and clavulanic acid treatment of subcutaneous abscesses caused by Bacteroides fragilis alone or in combination with aerobic bacteria.

A subcutaneous abscess model was utilized in investigating the usefulness of various antimicrobial combinations in the treatment of mixed aerobic-anaerobic infections in mice. The infected animals were treated for seven days with single or combined antimicrobial therapy. The single agents used were penicillin, clavulanic acid, oxacillin, metronidazole, and gentamicin. The antimicrobial combinations used were penicillin plus clavulanic acid and metronidazole plus penicillin, oxacillin, or gentamicin. Administration of a single agent was effective in treating abscesses caused by a single susceptible organism. The only effective therapies for mixed infections were the combinations of penicillin plus clavulanic acid or metronidazole plus gentamicin. This study demonstrated the efficacy of penicillin and clavulanic acid in the treatment of infections caused by Bacteroides fragilis alone or in combination with beta-lactamase-producing aerobic bacteria.

Abscess↗
PubMed1983

In-vivo protection of group A beta-haemolytic streptococci from penicillin by beta-lactamase-producing Bacteroides species.

The incidence of persistent group A beta-haemolytic streptococci in tonsils, despite penicillin therapy, has increased in recent years. beta-Lactamase-producing organisms have previously been recovered from 74% of patients with persisting group A streptococci. We investigated the possibility that beta-lactamase-producing strains of Bacteroides spp. can protect streptococci from penicillin. A mixed infection was induced in mice in the form of a subcutaneous abscess involving a penicillin-susceptible group A streptococcus, and a beta-lactamase-producing strain of either Bact. melaninogenicus or Bact. fragilis. The infected animals were treated for seven days with parenteral penicillin, penicillin and clavulanic acid or clindamycin. Penicillin treatment prevented the formation of abscesses in animals inoculated with group A streptococci alone, but not in those inoculated with group A streptococci and Bacteroides spp. We attributed this resistance to penicillin therapy, and the subsequent formation of abscesses in mice, to protection of the streptococci from penicillin by beta-lactamase-producing strains of Bacteroides spp. Effective therapy for mixed infections was achieved when clavulanic acid, a beta-lactamase inhibitor, was administered with penicillin. A similar effect was noted with clindamycin, which is active against both group A streptococci and Bacteroides spp.

Abscess↗